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Medium, CVSS 6.5amended

Cloudreve: Denial of Service - Image decompression / pixel bomb in thumbnail & avatar decoding crashes the server

CVE-2026-55497GHSA-g9j2-8w95-3vwv

What to do

Partial vendor fix. Follow the primary source's mitigation guidance and check back for a fix.

This page has no inventory attached, so it cannot say whether you are affected. A vendor fix is not proof that your deployment is fixed.

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Affected packages

  • Go github.com/cloudreve/Cloudreve/v3

    Affected
    <= 3.0.0-20250225100611-da4e44b77af4
    Fixed in
    no fixed version recorded

  • Go github.com/cloudreve/Cloudreve

    Affected
    every version
    Fixed in
    no fixed version recorded

  • Go github.com/cloudreve/Cloudreve/v4

    Affected
    < 4.0.0-20260613024411-3607f79bb44c
    Fixed in
    4.0.0-20260613024411-3607f79bb44c

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS
6.5 · CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
EPSS
  • CVE-2026-55497: 0.53% estimated exploitation activity in the next 30 days; percentile 44.90 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.
Source description

As published by the source; long descriptions are shortened.

Summary Cloudreve's built-in image processor decodes user-supplied images with Go's standard-library decoders (image/png, image/jpeg, image/gif) and guards only the compressed file size — never the decoded pixel dimensions. Go's decoders allocate a pixel buffer sized bytesPerPixel × width × height taken straight from the image header (e.g. a PNG's IHDR), with no upper bound on width/height. A tiny (tens-of-bytes) image that declares enormous dimensions therefore forces a multi-gigabyte-to-terabyte allocation (make([]uint8, …)), exhausting memory. The resulting out-of-memory condition is a fatal Go runtime error / kernel OOM-kill that recover() cannot catch, terminating the whole Cloudreve process for all users. Two reachable sinks share the same root cause: 1. Avatar upload (PUT /api/v4/user/setting/avatar) — decodes synchronously in the request handler. Any authenticated user. Cleanest single-request PoC. 2. Thumbnail generation (built-in generator, enabled by default) — decodes in…

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 2 · amended ·

    Amended from ghsa record GHSA-g9j2-8w95-3vwv

  2. Revision 1 · created ·

    Published from osv record GO-2026-6100

Agent brief

Preview the exact text before you copy it. Commands are read-only suggestions; review them before running anything.

# Patch Next advisory brief: CVE-2026-55497

Advisory: Cloudreve: Denial of Service - Image decompression / pixel bomb in thumbnail & avatar decoding crashes the server
IDs: CVE-2026-55497, GHSA-g9j2-8w95-3vwv
Record: https://patchnext.com/advisories/cve-2026-55497 (revision 2, source checked 26 Oct 2026, 15:27 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 6.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Partial vendor fix; fixed versions by package: github.com/cloudreve/Cloudreve/v4 4.0.0-20260613024411-3607f79bb44c. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/cloudreve/Cloudreve/v3: affected <= 3.0.0-20250225100611-da4e44b77af4
- Go github.com/cloudreve/Cloudreve: affected every version
- Go github.com/cloudreve/Cloudreve/v4: affected < 4.0.0-20260613024411-3607f79bb44c; fixed in 4.0.0-20260613024411-3607f79bb44c

## Suggested inspection (read-only)
- Go github.com/cloudreve/Cloudreve/v3: check the installed version with your package manager.
- Go github.com/cloudreve/Cloudreve: check the installed version with your package manager.
- Go github.com/cloudreve/Cloudreve/v4: check the installed version with your package manager.

## Supported action
No complete vendor fix is recorded. Follow the primary source's mitigation guidance and check this record again before closing anything.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on github.com/cloudreve/Cloudreve/v3, github.com/cloudreve/Cloudreve, github.com/cloudreve/Cloudreve/v4.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GO-2026-6100 (OSV record GO-2026-6100 lists affected ranges: Go github.com/cloudreve/Cloudreve >=0; Go github.com/cloudreve/Cloudreve/v3 >=0; Go github.com/cloudreve/Cloudreve/v4 >=0 <4.0.0-20260613024411-3607f79bb44c (fixed))
- Verified: https://github.com/advisories/GHSA-g9j2-8w95-3vwv (GitHub-reviewed advisory GHSA-g9j2-8w95-3vwv lists affected ranges: Go github.com/cloudreve/Cloudreve/v4 >=0 =0 <=3.0.0-20250225100611-da4e44b77af4)

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